The invention relates to a method and a device for automatic locking of an automobile and in particular for automatic locking of the doors when an occupant, and in particular the driver, leaves the automobile.
Automobiles are known which include a system for access and starting without manual intervention, known as hands-free access and starting; such a system permits the unlocking of the doors and/or other antitheft security devices of the automobile without manual intervention by the user.
For this, the user is provided with a recognition means, or “identifier”, which permits a control unit for the unlocking of the automobile to recognise the authorised user when the user is close to a door of the automobile and, generally, when the user actuates the opening handle or more generally any device for controlling the external opening of the door.
The identifier may consist for example of an electronic card or a transmitter supplying an identification code which must be recognised by the control unit for unlocking of the automobile in order to permit the unlocking manoeuvre.
Vehicles having a hands-free access and starting system currently necessitate an action by the user when the latter leaves the automobile in order for locking of the automobile, and for example locking of the doors, to be carried out. Generally, in order to activate the locking means the user actuates a push-button situated on the external opening control of the door.
There is at present a demand by users of vehicles having the hands-free access and starting function for not only unlocking but also locking of the automobile to be carried out, with great operating reliability, in a totally automatic manner without manual intervention when the user leaves his automobile.
Automatic locking of the vehicle necessitates that certain precautions be taken in order to avoid untimely locking before the driver has got out and moved away from the vehicle or when passengers have remained inside the vehicle.
It is also necessary for the locking device to be controlled on the basis of totally reliable data concerning the presence or absence of an identifier close to the automobile.
In order to design an automatic locking device which takes account of all the possible cases and only carries out locking deliberately, it is necessary to carry out a large number of checks which may necessitate special installation of detectors in the interior or on the exterior of the automobile.
A priori, a locking system which satisfies all the requirements is therefore a complex and costly device.
The vehicles which are equipped with a hands-free access and starting system generally includes means for detecting the presence or absence of a user equipped with an identifier in a defined zone, generally outside the automobile and close to a door, these detection means generally including one or several external antennas.
The automobiles usually also include means for detecting the open or closed condition of the doors used as a security device in order to signal this open and closed condition on a display means of the instrument panel or in order to prohibit the starting of the automobile automatically in the event that a door has remained open.
The automobiles also include means which make it possible to detect whether the engine of the vehicle is stopped or running.
These means have never been used in order to carry out automatic locking of an automobile equipped with a hands-free access and starting system in a totally reliable manner.